Ingeniero

Properties and Uses
Physical properties : Commercial carbon disulfide often possesses a strong disagreeable and fetid odor due to the presence of very small amounts of strong smelling organic sulfur compounds. The pure product has an odor that is somewhat pleasing and ethereal in nature. Carbon disulfide is highly flammable, having an explosive range, percent by volume in air, from 1.25 to 50.The flash point is –30º C and auto ignition occurs at 100C or even lower under certain conditions. Thus carbon disulfide will flash if the liquid is brought into contact with open steam pipes. Its solubility in water is 0.22 g/100 ml at 22º C. It is an effective solvent for many organic compounds. Thermally, carbon disulfide is a rather stable compound, as would be inferred from its thermodynamicproperties. The strength of the C–S bond is 131.7 Kcal. The compound is quite sensitive to light, especially if impurities are present, and will change to a yellowish color in a few days if left in diffuse sunlight.

Physical Constants for carbon disulfide : Property Freezing Point Boiling Point Critical volume Vapor density (air = 1) Refractive index (25º C) Latent heat of fusion, H m Latentheat of vaporization, Hv 298º K Heat of formation, H f 298º K Entropy, SM 298º K Heat of combustion, H C Viscosity, cP (at temp,º C) Numerical Value – 111.6º C 46.25 º C 1.745 ml/g 2.62 1.6294 1,050 cal/g-mol 6,550 cal/g-mol 27,580 cal/g-mol 20,900 cal/g-mol 56.84 cal/g-mol 0.3453(0) 0.3032(15) 0.2916(20) 0.2660(35) 33.07(20) 33.25(30) 30.79(40) 1.2931(0)

Surface tension, dyne/cm at temp,º CDensity at (temp,º C), g/ml

Density at (temp,º C), g/ml

1.2632(15) 1.2559(25) 1.2250(46.25)

Chemical Properties:

Carbon disulfide reacts to some extent with aqueous alkali to form a mixture of carbonate and thiocarbonate, 3CS2 + 6 KOH

Æ K CO
2

3

+ 2 K2CS3 + H2O

With alcoholic alkali, reaction with carbon disulfide takes place readily with the formation of xanthates,CS2 + NaOH + C2H5OH

Æ

SC(OC2H5)(SNa) + H2O

Alkali phenolates react with carbon disulfide to form alkali xanthates (sodium cellulose dithiocarbonate), RcelluloseONa + CS2

Æ SC(OR

cellulose)(SNa)

The solid xanthate, thus formed, is dissolved in caustic soda solution to form “viscose” solution. From this solution regenerated cellulose (viscose rayon) is prepared by neutralizationwith acid.

Another important reaction is the chlorination of carbon disulfide to produce carbon tetrachloride. Chlorine in the presence of iron as a catalyst, sulfur dichloride (SCl2), and sulfur monochloride (S2Cl2) are used as chlorinating agents. The reaction proceeds in two steps, as follows: CS2 + 3 Cl2

Æ

CCl4 + S2Cl2

CS2 + 2 S2Cl2

Æ

CCl4 + 6 S

Carbon tetrabromide is formedin a similar fashion by the action of bromine on carbon disulfide. Treatment of carbon disulfide with chlorine and trace of iodine gives trichloromethanesulfenyl chloride, CCl3SCl. Reduction of the latter compound with stannous chloride or tin and hydrochloric acid produces thiophosgene, CSCl2. This compound is useful as an intermediate of many organic sulfur compounds.

Carbon disulfidereacts with boiling aniline to form thiocarbanilide according to the equation, CS2 + 2 C6H5NH2

Æ

SC(NHC6H5)2 + H2S

Thiocarbanilide is used in dyes, as a vulcanization accelerator, and in synthetic organic pharmaceuticals, etc. carbon disulfide also reacts with primary and secondary amines to give substituted ammonium salts of N-substituted dithiocarbamic acids, RNHCS-SNH3R and R2NCSSNH2R2.Ammonium dithiocarbamate is prepared by the addition of carbon disulfide to a solution of alcoholic ammonia, 2 NH3 + CS2

Æ Æ

NH2CSSNH4

Sodium dimethyl dithiocarbamate is manufactured by the reaction of carbon disulfide with dimethylamine and caustic, (CH3)2NH + CS2 + NaOH (CH3)2NC(S)SNa + H2O

Carbon disulfide reacts with various compounds to produce carbon oxysulfide. Thus, carbon...